Communication receiver for selecting between scanning and locking to a channel and method therefor

Abstract

A channel scanning communication receiver (204) operates in a system that transmits information in cycles (104) including subsequences (106). The receiver determines whether to operate in a scanning or locked mode by making (302) signal quality pass/fail decisions for subsequences transmitted in a predetermined group of cycles. A decision is made for a transmission of a subsequence, and subsequence active/inactive decisions are made (304) for the subsequences transmitted in the predetermined group of cycles, based upon the signal quality pass/fail decisions made for the subsequences. The receiver determines (306) whether the system is time-shared or continuous, based upon how many active decisions and inactive decisions are made, and selects (310, 312) the scanning or locked mode in accordance with predetermined rules for time-shared or continuous systems, according to whether the system is time-shared or continuous.

What is claimed is: 
     
       1. A method in a channel scanning communication receiver operating in a communication system that periodically transmits information in a plurality of cycles, a cycle comprising a plurality of subsequences, the method for determining whether to operate in a scanning mode or in a locked mode, the method comprising the steps of: making a plurality of signal quality pass/fail decisions for the plurality of subsequences transmitted in a predetermined plurality of cycles, a decision made for a transmission of a subsequence;   making a plurality of subsequence active/inactive decisions for ones of the plurality of subsequences transmitted in the predetermined plurality of cycles, based upon the plurality of signal quality pass/fail decisions made for the plurality of subsequences;   determining whether the communication system is time-shared, based upon how many active decisions and how many inactive decisions are made for the ones of the plurality of subsequences; and   selecting from operation in the scanning mode and operation in the locked mode in accordance with predetermined rules for time-shared systems, in response to the determining step finding that the communication system is time-shared.   
     
     
       2. The method of claim 1, wherein the subsequence comprises a plurality of synchronous batches, and   wherein one of the plurality of synchronous batches assigned for use by the communication receiver is defined as an active batch, and   wherein the step of making a plurality of signal quality pass/fail decisions for the plurality of subsequences comprises the step of monitoring the active batch in ones of the plurality of subsequences.     
     
     
       3. The method of claim 1, wherein the step of making a plurality of signal quality pass/fail decisions comprises for a transmission of the subsequence the steps of: determining that signal quality passes in response to (a) detecting expected information, and (b) counting less than a predetermined number of uncorrectable errors in the expected information; and   otherwise determining that the signal quality fails.   
     
     
       4. The method of claim 1, wherein the step of selecting from operation in the scanning mode and operation in the locked mode comprises the step of changing from a locked mode to a scanning mode in response to the plurality of signal quality pass/fail decisions being "fail" in M most recent transmissions of the plurality of subsequences, M being a predetermined positive integer value.   
     
     
       5. The method of claim 1, wherein the step of making a plurality of subsequence active/inactive decisions comprises the steps of: maintaining a plurality of records of N most recent signal quality pass/fail decisions corresponding to the ones of the plurality of subsequences transmitted in the predetermined plurality of cycles, N being a predetermined positive integer value;   maintaining a plurality of sums corresponding to the plurality of subsequences, a sum indicative of how many of the N most recent signal quality pass/fail decisions for a corresponding one of the plurality of records are "pass";   defining ones of the plurality of subsequences to be "inactive" in response to corresponding ones of the plurality of sums being equal to zero; and   defining the ones of the plurality of subsequences to be "reliably active" in response to the corresponding ones of the plurality of sums being greater than a predetermined value.   
     
     
       6. The method of claim 5, wherein the step of selecting from operation in the scanning mode and operation in the locked mode comprises the steps of: changing from a scanning mode to a locked mode in response to at least one of the plurality of subsequences being defined as reliably active.   
     
     
       7. The method of claim 5, wherein the step of determining whether the communication system is time-shared comprises the steps of: determining the communication system to be time-shared in response to at least one of the plurality of subsequences being defined as inactive and at least one of the plurality of subsequences being defined as reliably active; and   otherwise determining the communication system to be continuous.   
     
     
       8. A method in a channel scanning communication receiver operating in a communication system that periodically transmits information in a plurality of cycles, a cycle comprising a plurality of subsequences, the method for determining whether to operate in a scanning mode or in a locked mode, the method comprising the steps of: making a plurality of signal quality pass/fail decisions for the plurality of subsequences transmitted in a predetermined plurality of cycles, a decision made for a transmission of a subsequence;   making a plurality of subsequence active/inactive decisions for ones of the plurality of subsequences transmitted in the predetermined plurality of cycles, based upon the plurality of signal quality pass/fail decisions made for the plurality of subsequences;   determining whether the communication system is time-shared, based upon how many active decisions and how many inactive decisions are made for the ones of the plurality of subsequences; and   selecting from operation in the scanning mode and operation in the locked mode in accordance with predetermined rules for continuous systems, in response to the determining step finding that the communication system is continuous.   
     
     
       9. The method of claim 8, wherein the subsequence comprises a plurality of synchronous batches, and   wherein one of the plurality of synchronous batches assigned for use by the communication receiver is defined as an active batch, and   wherein the step of making a plurality of signal quality pass/fail decisions for the plurality of subsequences comprises the step of monitoring the active batch in ones of the plurality of subsequences.     
     
     
       10. The method of claim 8, wherein the step of making a plurality of signal quality pass/fail decisions comprises for a transmission of the subsequence the steps of: determining that signal quality passes in response to (a) detecting expected information, and (b) counting less than a predetermined number of uncorrectable errors in the expected information; and   otherwise determining that the signal quality fails.   
     
     
       11. The method of claim 8, wherein the step of making a plurality of subsequence active/inactive decisions comprises the steps of: maintaining a plurality of records of N most recent signal quality pass/fail decisions corresponding to the ones of the plurality of subsequences transmitted in the predetermined plurality of cycles, N being a predetermined positive integer value;   maintaining a plurality of sums corresponding to the plurality of subsequences, a sum indicative of how many of the N most recent signal quality pass/fail decisions for a corresponding one of the plurality of records are "pass";   defining ones of the plurality of subsequences to be "inactive" in response to corresponding ones of the plurality of sums being equal to zero; and   defining the ones of the plurality of subsequences to be "reliably active" in response to the corresponding ones of the plurality of sums being greater than a predetermined value.   
     
     
       12. The method of claim 8, wherein the step of determining whether the communication system is time-shared comprises the steps of: determining the communication system to be time-shared in response to at least one of the plurality of subsequences being defined as inactive and at least one of the plurality of subsequences being defined as reliably active; and   otherwise determining the communication system to be continuous.   
     
     
       13. The method of claim 8, further comprising the step of maintaining a record of P signal quality pass/fail decisions for P most recent transmissions of the plurality of subsequences, P being a predetermined positive integer value.   
     
     
       14. The method of claim 13, wherein the step of selecting from operation in the scanning mode and operation in the locked mode comprises the step of changing from the locked mode to the scanning mode in response to the plurality of signal quality pass/fail decisions being "fail" in more than a pre-programmable number of the P most recent transmissions.   
     
     
       15. The method of claim 13, wherein the step of selecting from operation in the scanning mode and operation in the locked mode comprises the step of changing from the scanning mode to the locked mode in response to the plurality of signal quality pass/fail decisions being "pass" in more than a pre-programmable number of the P most recent transmissions.   
     
     
       16. A channel scanning communication receiver for operating in a communication system that periodically transmits information in a plurality of cycles, a cycle comprising a plurality of subsequences, the communication receiver determining whether to operate in a scanning mode or in a locked mode, the communication receiver comprising: an antenna for intercepting a radio signal comprising the information;   a receiver element coupled to the antenna for demodulating the information;   a processing system coupled to the receiver element for processing the information; and   a user interface coupled to the processing system for conveying the information to a user,   wherein the processing system is programmed for executing the steps of: making a plurality of signal quality pass/fail decisions for the plurality of subsequences transmitted in a predetermined plurality of cycles, a decision made for a transmission of a subsequence;   making a plurality of subsequence active/inactive decisions for ones of the plurality of subsequences transmitted in the predetermined plurality of cycles, based upon the plurality of signal quality pass/fail decisions made for the plurality of subsequences;   determining whether the communication system is time-shared, based upon how many active decisions and how many inactive decisions are made for the ones of the plurality of subsequences; and   selecting from operation in the scanning mode and operation in the locked mode in accordance with predetermined rules for time-shared systems, in response to the determining step finding that the communication system is time-shared.     
     
     
       17. The communication receiver of claim 16, wherein the subsequence comprises a plurality of synchronous batches, and   wherein one of the plurality of synchronous batches assigned for use by the communication receiver is defined as an active batch, and   wherein the step of making a plurality of signal quality pass/fail decisions for the plurality of subsequences comprises the step of monitoring the active batch in ones of the plurality of subsequences.     
     
     
       18. The communication receiver of claim 16, wherein the step of making a plurality of signal quality pass/fail decisions comprises for a transmission of the subsequence the steps of: determining that signal quality passes in response to (a) detecting expected information, and (b) counting less than a predetermined number of uncorrectable errors in the expected information; and   otherwise determining that the signal quality fails.   
     
     
       19. The communication receiver of claim 16, wherein the step of selecting from operation in the scanning mode and operation in the locked mode comprises the step of changing from a locked mode to a scanning mode in response to the plurality of signal quality pass/fail decisions being "fail" in M most recent transmissions of the plurality of subsequences, M being a predetermined positive integer value.   
     
     
       20. The communication receiver of claim 16, wherein the step of making a plurality of subsequence active/inactive decisions comprises the steps of: maintaining a plurality of records of N most recent signal quality pass/fail decisions corresponding to the ones of the plurality of subsequences transmitted in the predetermined plurality of cycles, N being a predetermined positive integer value;   maintaining a plurality of sums corresponding to the plurality of subsequences, a sum indicative of how many of the N most recent signal quality pass/fail decisions for a corresponding one of the plurality of records are "pass";   defining ones of the plurality of subsequences to be "inactive" in response to corresponding ones of the plurality of sums being equal to zero; and   defining the ones of the plurality of subsequences to be "reliably active" in response to the corresponding ones of the plurality of sums being greater than a predetermined value.   
     
     
       21. The communication receiver of claim 20, wherein the step of selecting from operation in the scanning mode and operation in the locked mode comprises the steps of: changing from a scanning mode to a locked mode in response to at least one of the plurality of subsequences being defined as reliably active.   
     
     
       22. The communication receiver of claim 20, wherein the step of determining whether the communication system is time-shared comprises the steps of: determining the communication system to be time-shared in response to at least one of the plurality of subsequences being defined as inactive and at least one of the plurality of subsequences being defined as reliably active; and   otherwise determining the communication system to be continuous.   
     
     
       23. A channel scanning communication receiver for operating in a communication system that periodically transmits information in a plurality of cycles, a cycle comprising a plurality of subsequences, the communication receiver determining whether to operate in a scanning mode or in a locked mode, the communication receiver comprising: an antenna for intercepting a radio signal comprising the information;   a receiver element coupled to the antenna for demodulating the information;   a processing system coupled to the receiver element for processing the information; and   a user interface coupled to the processing system for conveying the information to a user,   wherein the processing system is programmed for executing the steps of: making a plurality of signal quality pass/fail decisions for the plurality of subsequences transmitted in a predetermined plurality of cycles, a decision made for a transmission of a subsequence;   making a plurality of subsequence active/inactive decisions for ones of the plurality of subsequences transmitted in the predetermined plurality of cycles, based upon the plurality of signal quality pass/fail decisions made for the plurality of subsequences;   determining whether the communication system is time-shared, based upon how many active decisions and how many inactive decisions are made for the ones of the plurality of subsequences; and   selecting from operation in the scanning mode and operation in the locked mode in accordance with predetermined rules for continuous systems, in response to the determining step finding that the communication system is continuous.     
     
     
       24. The communication receiver of claim 23, wherein the subsequence comprises a plurality of synchronous batches, and   wherein one of the plurality of synchronous batches assigned for use by the communication receiver is defined as an active batch, and   wherein the step of making a plurality of signal quality pass/fail decisions for the plurality of subsequences comprises the step of monitoring the active batch in ones of the plurality of subsequences.     
     
     
       25. The communication receiver of claim 23, wherein the step of making a plurality of signal quality pass/fail decisions comprises for a transmission of the subsequence the steps of: determining that signal quality passes in response to (a) detecting expected information, and (b) counting less than a predetermined number of uncorrectable errors in the expected information; and   otherwise determining that the signal quality fails.   
     
     
       26. The communication receiver of claim 23, wherein the step of making a plurality of subsequence active/inactive decisions comprises the steps of: maintaining a plurality of records of N most recent signal quality pass/fail decisions corresponding to the ones of the plurality of subsequences transmitted in the predetermined plurality of cycles, N being a predetermined positive integer value;   maintaining a plurality of sums corresponding to the plurality of subsequences, a sum indicative of how many of the N most recent signal quality pass/fail decisions for a corresponding one of the plurality of records are "pass";   defining ones of the plurality of subsequences to be "inactive" in response to corresponding ones of the plurality of sums being equal to zero; and   defining the ones of the plurality of subsequences to be "reliably active" in response to the corresponding ones of the plurality of sums being greater than a predetermined value.   
     
     
       27. The communication receiver of claim 23, wherein the step of determining whether the communication system is time-shared comprises the steps of: determining the communication system to be time-shared in response to at least one of the plurality of subsequences being defined as inactive and at least one of the plurality of subsequences being defined as reliably active; and   otherwise determining the communication system to be continuous.   
     
     
       28. The communication receiver of claim 23, further comprising the step of maintaining a record of P signal quality pass/fail decisions for P most recent transmissions of the plurality of subsequences, P being a predetermined positive integer value.   
     
     
       29. The communication receiver of claim 28, wherein the step of selecting from operation in the scanning mode and operation in the locked mode comprises the step of changing from the locked mode to the scanning mode in response to the plurality of signal quality pass/fail decisions being "fail" in more than a pre-programmable number of the P most recent transmissions.   
     
     
       30. The communication receiver of claim 28, wherein the step of selecting from operation in the scanning mode and operation in the locked mode comprises the step of changing from the scanning mode to the locked mode in response to the plurality of signal quality pass/fail decisions being "pass" in more than a pre-programmable number of the P most recent transmissions.